1. Field of the Invention
The present invention relates to an emission control driver and an organic light emitting display (OLED) device having the same and, more particularly, to a system-on-panel (SOP)-type emission control driver which generates signals to control emission of pixels and an OLED device having the same.
2. Discussion of the Background
Flat panel displays (FPDs) have been developed because they can be made smaller and lighter than display devices using cathode ray tubes (CRTs). In turn, FPD technology has given rise to liquid crystal displays (LCDs), field emission displays (FEDs), plasma display panels (PDPs), and organic light emitting displays (OLEDs). Among these FPDs, the PDP may have a large screen, but suffers from low luminance and poor luminous efficiency resulting in high power consumption. Moreover, the LCD has a relatively slow response speed and consumes a large quantity of power since it employs a backlight.
However, since the OLED makes use of an organic material to emit light, it has a wider viewing angle and faster response speed than the LCD. Also, the OLED is an emissive display that obtains good contrast and visibility. Further, the OLED consumes less power and can be made thin and lightweight because it needs no backlight.
Nevertheless, when the OLED is constructed to have a large screen, the dimensions of an electroluminescent (EL) panel used for a glass substrate with the OLED are limited by fabricating process limitations. Also, if the screen is too large, there is a greater probability of a defect occurring somewhere on the screen. Thus, a reduction in yield is unavoidable, and it is difficult to obtain uniformity across the screen.
As a solution to the above problems of the OLED, a tiling technique has been developed. In the tiling technique, a plurality of EL panels are bonded together like tiles to form a single panel.
Each of the EL panels includes a plurality of pixels to display a predetermined image similar to a conventional OLED. In each of the EL panels, a scan driver applies a scan signal for enabling the pixels, and a data driver applies a data signal to a selected pixel. Also, an emission control driver applies an emission control signal to each of the pixels in order to control the exact programming of the data signal and the time required for an emission operation.
As described above, the scan driver, the data driver, and the emission control driver, which transmit various signals to drive the EL panels, may be electrically connected to each of the EL panels in various manners.
For example, the scan driver, the data driver, and the emission control driver may be mounted as chips on a tape carrier package (TCP) that is bonded and electrically connected to each of the EL panels. Alternatively, the drivers may be mounted as chips on a flexible printed circuit (FPC) or a film that is bonded and electrically connected to each of the EL panels. The latter technique is referred to as a chip-on-flexible board (or chip-on-film) (COF) technique. In another method, the drivers are directly mounted on a glass substrate of the EL panel. This method is referred to as a chip-on-glass (COG) technique. These methods are costly and complicate the modules because the drivers should be separately designed and electrically connected to one another.
To overcome these drawbacks, a system-on-panel (SOP) technique has been recently developed. Also, there have been attempts at designing a pixel portion, scan and emission control drivers, and/or a data driver in each EL panel, for constructing all systems in the EL panels.
In the OLED using the tiling technique, when each EL panel is formed as an SOP type, it is easy to bond the EL panels to one another. The SOP technique reduces the area of the drivers, in addition to the cost and labor associated with designing integrated circuits (ICs) for the drivers.
However, in order to develop the SOP-type OLED, it is necessary to consider many internal circumstances and conditions of the EL panels, such as a driving frequency and electron mobility of the data driver and/or the scan and emission control drivers. It is currently still difficult to design the data driver within a panel because the data driver needs a high driving frequency.
Accordingly, the data driver is formed as an IC using complementary metal oxide semiconductor (CMOS) technology and connected to the EL panel, while the scan driver and/or the emission control driver are formed within the EL panel.
Therefore, there is a need for a simple circuit construction in which a SOP-type scan driver and emission control driver can be optimally driven within the EL panel.